Theoretical investigation of the titanium—nitrogen heterofullerenes evolved from the smallest fullerene

In this survey, we are performed kinetic stability, global reactivity, atomic polar tensor (APT) charge and counter plots of Ti–N heterofullerenes developed from C20 fullerene with the molecular formula of C20-2nTinNn (n = 1–8), at B3PW91/6-311+G∗ level of theory. Also, we are investigated substituent effect of titanium and nitrogen heteroatoms on deuterium adsorption of the heterofullerenes according to density functional theory (DFT). Substituting of Ti–N units with various topology in the cap or equatorial position of heterofullerenes, changes significantly their electronic properties and causes different frontier molecular orbital energy separation (ΔEHOMO-LUMO). Hence, C18Ti1N1 and C10Ti5N5 are found as the best insulated species, while C12Ti4N4 and C4Ti8N8 are considered as the strongest conductive nanocage. Also, C14Ti3N3 cage shows the highest positive APT charge on Ti atom (+1.357, +1.053), while C12Ti4N4 cage shows the lowest positive APT charge on Ti atom (+0.031, −0.292). Accordingly, C14Ti3N3, and C12Ti4N4 exhibit the lowest, and the highest global electrophilicity; ω of 2.58, and 7.01 eV, respectively. As six D2 molecules are approached the C14Ti3N3 heterofullerene, its ΔEHOMO-LUMO (Eg) is increased from 1.29 eV in C14Ti3N3 heterofullerene to 2.11 eV in D2/C14Ti3N3 complex (∼+63.57%) indicating high sensitivity of it to adsorption of six D2 molecules through an exothermic process. As sixteen D2 molecules approaches the C4Ti8N8 nanocage, its Eg reduces from 0.97 to 0.73 eV (∼−24.74%) indicating high electrical conductivity of D2/C4Ti8N8 complex. Therefore, C4Ti8N8 as hopeful sensor, can be generate electrical signals when the D2 molecules approach.